The earthwork walls are the original Fort D, as constructed in 1861 and restored in 1936. A palisade wall, probably made of upright logs, constituted the rear wall and was pierced by a gate. The gap in the south wall may have been a “sally” port, allowing soldiers access to the rifle pits below the parapet. The fort was armed with three 32-pounder cannons and two 24-pounder cannons; all mounted on movable siege carriages. A 32-pounder cannon was a smoothbore cannon that could fire a 32-pound solid round shot over one mile. The cannon plus carriage probably weight more than four tons.